Tape drive data reclamation

ABSTRACT

The method, computer program product, and computer system may include a computing device which may generate a list of data to be copied from a plurality of source media to a target medium. The computing device may identify a first type of data in the generated list of data with the first type of data being pre-migrated data. The computing device may reclaim the first type of data from a primary storage tier to the target medium with the target medium being associated with the first drive. The computing device may identify a second type of data in the generated list of data, the second type of data being migrated data, and reclaim the second type of data from at least one secondary source medium to the target medium using the first drive and a second drive. The secondary source medium may be associated with the second drive.

BACKGROUND

The present invention relates generally to a method, system, andcomputer program for tape drive data reclamation. More particularly, thepresent invention relates to a method, system, and computer program forshortening a period of time during which two drives are simultaneouslyused during data reclamation.

Hierarchical storage management (HSM) is a known technology thatrealizes efficient use of a limited storage capacity. HSM is a schemefor arranging data that is frequently referred to in a high-speed andhigh-cost primary storage unit, such as a redundant array of independentdisks (RAID) and a solid state drive (SSD), and arranging data that isreferred to less frequently in a low-speed and low-cost secondarystorage unit. HSM may be implemented in, for example, IBM® products suchas the TS7700 Virtualization Engine and IBM® Spectrum Archive™Enterprise Edition.

A state where a certain piece of data is only stored in a primarystorage unit is called a “resident” state, a state where a certain pieceof data is stored not only in the primary storage unit but also in asecondary storage unit is called a “pre-migrated” state, and a statewhere a certain piece of data is only stored in the secondary storageunit is called a “migrated” state. For example, all pieces of TS7700data are first stored in the primary storage unit and thus placed in theresident state. After several minutes, the pieces of data are copied tothe secondary storage unit and thus placed in the pre-migrated state.The pieces of data will be then be fully moved to the secondary storageunit when the system has only a very little disk space remaining; thusplacing the pieces of data in the migrated state.

Storage products such as the IBM® TS7700 Virtualization Engine and IBM®Spectrum Archive™ Enterprise Edition adopt a magnetic tape as thesecondary storage unit. When a certain piece of data is written to amagnetic tape, which is a sequential-access medium, and the same pieceof data is subsequently updated, the piece of data that has been updatedis appended to the end of the tape while the previous data is handled asan invalid area. When updates to the data frequently occur, theproportion of the invalid area increases, causing relative decrease inthe capacity of the tape.

As a scheme for solving this problem, a technique called reclamation isknown. Reclamation is a technique of only reading valid data from a tapethat includes an invalid area and writing the valid data that has beenread to another tape. Reclamation requires two tape drives, for thesource tape from which the target data should be read and thedestination tape to which the data that has been read should be writtenshould be simultaneously accessed. In recent years, due to the increasein magnetic tape capacity, reclamation processing takes longer and thetwo tape drives are occupied longer, which is now recognized as adrawback of the technique. For example, the data transfer rate to a tapecompatible with an IBM® TS1150 tape drive is up to 360 megabytes persecond. When data is to be read from a tape medium of 10 terabytes usingtwo TS1150 tape drives to carry out reclamation, then the two drives maybe occupied for about eight hours (=10 (TB)/360 (MB/sec)).

The present invention solves the problem of prolonged occupation time ofthe two drives in the course of the reclamation processing.

BRIEF SUMMARY

An embodiment of the invention may include a method, computer programproduct and computer system for copying data from source media to targetmedia in a storage system. The method, computer program product, andcomputer system may include a computing device which may generate a listof data to be copied from a plurality of source media to a targetmedium. The computing device may identify a first type of data in thegenerated list of data with the first type of data being pre-migrateddata. The computing device may reclaim the first type of data from aprimary storage tier to the target medium with the target medium beingassociated with the first drive. The computing device may identify asecond type of data in the generated list of data, the second type ofdata being migrated data and reclaim the second type of data from atleast one secondary source medium to the target medium using the firstdrive and a second drive. The secondary source medium may be associatedwith the second drive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an overview of a hierarchical storage system, inaccordance with an embodiment of the invention.

FIG. 2 is a block diagram which illustrates a node constituting acluster of the hierarchical storage system, in accordance with anembodiment of the invention.

FIG. 3 is a block diagram which illustrates the hierarchical storagesystem, in accordance with an embodiment of the invention.

FIG. 4 is a block diagram which illustrates a reclamation module, inaccordance with an embodiment of the invention.

FIG. 5 is a flowchart illustrating a method for tape drive datareclamation.

FIG. 6 is a block diagram depicting the hardware components of the datareclamation system of FIG. 1, in accordance with an embodiment of theinvention;

FIG. 7 illustrates a cloud computing environment, in accordance with anembodiment of the invention; and

FIG. 8 illustrates a set of functional abstraction layers provided bythe cloud computing environment of FIG. 7, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION

Embodiments of the present invention will now be described in detailwith reference to the accompanying Figures.

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used to enablea clear and consistent understanding of the invention. Accordingly, itshould be apparent to those skilled in the art that the followingdescription of exemplary embodiments of the present invention isprovided for illustration purpose only and not for the purpose oflimiting the invention as defined by the appended claims and theirequivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces unless the context clearly dictatesotherwise. Now, the present invention will be described using particularembodiments, and the embodiments described hereafter are understood tobe only referred as examples and are not intended to limit the scope ofthe present invention.

One or more embodiments according to the present invention are directedto methods, computer systems, storage systems and computer programproducts for reclaiming data from a source medium to a target medium ina storage system.

Referring to series of FIGS. 1-3, a hierarchical storage system withdisk and tape tiers according to an exemplary embodiment of the presentinvention is described.

FIG. 1 illustrates an overview of the hierarchical storage system 100,in accordance with an embodiment of the invention. The hierarchicalstorage system 100 includes a cluster 110 with one or more nodes 112a-112 x. The cluster 110 provides a file system that allows forperforming file operations to the hierarchical storage system 100.

As shown in FIG. 1, the hierarchical storage system 100 may include aprimary storage tier, shared disk array 120 that includes one or moredisk caches 122 a-122 x, which are storage devices storing files. Eachnode 112 in the cluster 110 may be connected to the disk cache 122 a-122x in the shared disk array 120 via a SAN (Storage Area Network) fabric102. The SAN fabric 102 may include, but not limited to, FC (FibreChannel)—SAN based on a fiber channel network and/or IP (InternetProtocol)—SAN based on TCP (Transmission Control Protocol)/IP networkwith LAN (Local Area Network) switches.

The nodes 112 a-x may share the disk caches 122 a-122 x. The nodes 112a-x can access to the disk cache 122 a-122 x via the SAN fabric 102 andprovide also indirect file access for other nodes that do not connect tothe SAN fabric 102. Such file system distributed to the one or morenodes 112 a-112 x in the cluster 110, to which plurality of nodes (mayinclude client nodes) can access, is so called a clustered file systemor a distributed parallel file system. The clustered file system canprovide a global namespace, a striping functionality to stripe input andoutput over the nodes and an information lifecycle management (ILM)functionality.

The hierarchical storage system 100 may include further secondarystorage tier, tape library 130. The tape library 130 includes one ormore tape drives 132 a-132 x and one or more tape media 134 a-134 x. Anytape medium 134 a-134 x can be a medium for either source or target ofcopy operations. Each node 112 a-112 x in the cluster 110 may beconnected to the tape library 130 via SAN fabric, FC LVD (Low VoltageDifferential) SCSI (Small Computer System Interface) or SAS (SerialAttached SCSI) cables. Equipping the plurality of the tape drives 132a-132-x enables the node 112 a-112 x to access a set of the tape media134 a-134 x simultaneously. The tape drive 132 a-132 x may be occupiedby the node at a point in time and may be used alternately. The tapedrives 132 a-132 x may accept LTO (Linear Tape-Open) Ultrium 5 or latertape cartridges, which support LTFS (Liner Tape File System™), or otherproprietary formats.

The tape library 130 is managed by the computer system 200, which may bea tape file system such as, but not limited to, LTFS (Liner Tape FileSystem™) and integrated to the clustered file system so that at leastpart of data in the shared disk array 120 is stored on tape media 134a-134 x in the tape library 130. Files may migrate from the shared diskarray 120 to the tape library 130 based on a predetermined migrationpolicy.

The hierarchical storage system 100 may include further a controlterminal 140. The control terminal 140 is a terminal device where anadministrative user can operate to issue manual request and to specifysettings of the hierarchical storage system. By using the controlterminal 140, the administrative user can specify settings of a novelreclamation and/or inter-generation copy process according to theexemplary embodiment of the present invention, which will be describedin more detail later. The administrative user can also issue manualrequest and specify schedules or policies for other functionalities ofthe hierarchical storage system 100 such as standard migration, recall,reconciliation, file placement, file management, etc.

As shown in FIG. 1, in the describing embodiment, the nodes 112 a-112 xare described to be connected to the disk caches 122 a-122 x in theshared disk array 120 and the nodes 112 a-112 x are described to beconnected to the tape drives 132 a-132 x in the tape library 130.However, the configuration of the hierarchical storage system 100 shownin FIG. 1 is only an example for typical storage system and is notintended to suggest any limitation.

For instance, in a particular embodiment, the shared disk array 120 maybe divided to one or more online storages and one or more nearlinestorages to construct a three or more tiered architecture. In anotherparticular embodiment, the hierarchical storage system may includefurther a flash storage tier on top of the hierarchical storage system.In further other embodiment, the storage system may have merely onenode, one disk cache and one tape drive to construct a hierarchicalstorage system. In further another embodiment, another type of asequential access medium may be used as a storage medium for both sourceand target in place of or in addition to the tape medium.

FIG. 2 illustrates a schematic diagram of an example node in accordancewith an example embodiment of the invention. The node 112 a is only oneexample of a suitable node and is not intended to suggest any limitationas to the scope of use or functionality of embodiments of the inventiondescribed herein. Regardless, the node 112 a is capable of beingimplemented and/or performing any of the functionality set forth herein.

The node 112 a is operational with numerous other general purpose orspecial purpose computing system environments or configurations.Examples of well-known computing systems, environments, and/orconfigurations that may be suitable for use with the node 112 a include,but are not limited to, personal computer systems, server computersystems, thin clients, thick clients, hand-held or laptop devices,multiprocessor systems, microprocessor-based systems, set top boxes,programmable consumer electronics, network PCs, minicomputer systems,mainframe computer systems, and distributed cloud computing environmentsthat include any of the above systems or devices, and the like.

The node 112 a may be described in the general context of computersystem-executable instructions, such as program modules, being executedby a computer system. Generally, program modules may include routines,programs, objects, components, logic, data structures, and so on thatperform particular tasks or implement particular abstract data types.

As shown in FIG. 2, the node 112 a is shown in the form of ageneral-purpose computing device. The components of the node 112 a mayinclude, but are not limited to, one or more processors (or processingunits) 10 and a memory 12 operatively coupled to the processors 10 by abus including a memory bus or memory controller, and a processor orlocal bus using any of a variety of bus architectures.

The node 112 a typically includes a variety of computer system readablemedia. Such media may be any available media that is accessible by thenode 112 a, and it includes both volatile and non-volatile media,removable and non-removable media.

The memory 12 can include computer system readable media in the form ofvolatile memory, such as random access memory (RAM). The node 112 a mayfurther include other removable/non-removable, volatile/non-volatilecomputer system storage media. By way of example only, the storagedevice 14 can be provided for reading from and writing to anon-removable, non-volatile magnetic media. Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus by one or more datamedia interfaces. As will be further depicted and described below, thestorage device 14 may include at least one program product having a set(e.g., at least one) of program modules that are configured to carry outthe functions of embodiments of the invention.

Program/utility, having a set (at least one) of program modules, may bestored in the storage device 14 by way of example, and not limitation,as well as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.

The node 112 a may also communicate with one or more peripherals such asa keyboard, a pointing device, etc.; a display; one or more devices thatenable a user to interact with the node 112 a; and/or any devices (e.g.,network card, modem, etc.) that enable the node 112 a to communicatewith one or more other computing devices via SAN fabric 102. Suchcommunication can occur via Input/Output (I/O) interfaces 18. Still yet,the node 112 a can communicate with one or more networks such as a localarea network (LAN) 104, a general wide area network (WAN), and/or apublic network (e.g., the Internet) via the network adapter 16. Asdepicted, the network adapter 16 communicates with the other componentsof the node 112 a via bus. It should be understood that although notshown, other hardware and/or software components could be used inconjunction with the node 112 a. Examples, include, but are not limitedto: microcode, device drivers, redundant processing units, external diskdrive arrays, RAID systems, tape drives, and data archival storagesystems, etc. The node 112 a may be interconnected with another node 112via a host channel adapter (HCA) such as InfiniBand (™).

Hardware and/or software components of the tape library 130, the tapedrives 132 a-132 x, the control terminal 140 may include, similar to thenode 112 a shown in FIG. 2, a processer, a memory, a read only memory, anetwork adapter, a I/O interface, and robotic mechanism, but not beshown in the drawings any more.

FIG. 3 illustrates a block diagram of the hierarchical storage system100 is. As shown in FIG. 3, the hierarchical storage system 100 includesa computer system 200 connected to the shared disk array 120 and thetape library 130. The computer system 200 may be composed of the nodes112 a-112 x in the cluster 110 shown in FIG. 1 and FIG. 2.

As shown in FIG. 3, the computer system 200 includes a clustered filesystem module 210; a storage management module 220; a reclamation module230; and a tape file system module 250.

The clustered file system module 210 may be a software component thatmanages the clustered file system on the shared disk array 120 in thehierarchical storage system 100. The tape file system module 250 may bea software component that allows for performing file operations to thetape media 134 a-134 x and providing interface to manipulate files onthe tape media 134 a-134 x in the tape library 130. The tape media 134a-134 x in the tape library 130 may be accessed as subdirectories undera mount point of the tape library 130.

The storage management module 220 may be a software component thatprovides integration of the clustered file system managed by theclustered file system module 210 with the tape file system managed bythe tape file system module 250. The storage management module 220manages standard migration and recall activities in the hierarchicalstorage system 100.

The reclamation module 230 may be a software component that provides thenovel reclamation function according to one or more embodiments of thepresent invention.

Before describing the novel reclamation function in detail, normalfunctionalities including standard migration and recall in thehierarchical storage system 100 will be described.

Migration is a process in which files are moved from the shared diskarray 120 to the tape media 134 a-134 x on the tape library 130. Themigration process may have plurality of modes. In a first mode, themigration process leaves behind a small stub file on the shared diskarray 120, which points the file body migrated to the tape medium. Themigration process in a second mode is so-called as a pre-migration, inwhich files are moved from the shared disk array 120 to the tape media134 a-134 x on the tape library 130 without replacing the file body witha stub file on the shared disk array 120. According to the pre-migrationmode, identical copies of the files are on both the disk and tape tiers,i.e. shared disk array 120, tape library 130. Recall is a process inwhich the migrated files are moved from the tape media 134 a-134 x backto the originating shared disk array 120 if an accessed file does notexist on the shared disk array 120.

The files newly created or overwritten to the hierarchical storagesystem 100 may initially be merely on the shared disk array 120, thusthe file state is initially “resident”. The files may be migrated fromthe shared disk array 120 to the tape library 130 by running themigration process in first mode, after which the file is a stub on thedisk and the identifiers of the tapes storing the copies are written tometadata. The file state of such file is referred to as “migrated”. Thefile may be recalled from the tape library 130 by recall activities whenan application attempts to read from the file. The file state of suchfile on both the disk and tape tiers, i.e. shared disk array 120 andtape library 130, is referred to as “pre-migrated”. Also the files maybe pre-migrated to the tape library 130 by running the migration processin second mode.

A desired reclamation function, e.g., in which the occupation time ofthe drives involved in reclamation is reduced by switching the storagemedia from which the source data to be reclaimed is read, is desired insome of the embodiments described herein.

FIG. 4 illustrates a block diagram of the reclamation module 230, inaccordance with an embodiment of the invention. In FIG. 4, a detailedblock diagram of the reclamation module 230 is depicted with othercomponents related to the novel reclamation function, which include thetape file system module 250, the plurality of the tape drives 132 a-132x, the plurality of the tape media 134 a-134 x, and the disk cache 122.

The tape medium that stores target files of reclamation is referred toas a source medium 134. The tape media that is used as a target (ordestination) of the reclamation is referred to as a target medium 134 t.For example, the tape drive 132 that holds the source medium 134, forexample, 134 a-134 c, is referred to as a source tape drive 132S and thetape drive 132 that holds the target medium 134, for example, 134 t, isreferred to as a target tape drive 132 t.

The reclamation is a process in which merely active data on the sourcemedium 134 a-134 c is copied to the target medium 134 t to defragment.Some particular implementations may automatically trigger thereclamation process when the ratio of the active data on the tape mediumfalls below a predetermined level. Since files stored on the shared diskarray 120 are often moved to the tape library 130 using the plurality ofthe tape drives 132 a-132 x at once, data are typically written tomultiple tape media 134 a-134 x evenly. Therefore, the multiple tapemedia 134 a-134 x may have to be involved in the reclamation processsimultaneously. Further, disk cache 122 a-122 x in shared disk array 120may be a source storage device that stores a plurality of files as atarget for migration which is performed during the reclamation process.For example, disk cache 122 a-122 x may store data which is in apre-migrated state, meaning the data is located both on the disk cache122 a-122 x and one or more of the tape media 134 a-c.

In this case, a lot of tape drives 132 a-132 x are occupied for thereclamation. Alternatively, the reclamation may continue for a long timewhen many tape media 134 a-134 x are processed by a single part of tapedrive 132 in a one by one manner. Consequently, other operations such asthe migrations and recalls may be prevented by drive occupation for thereclamation process. Therefore, embodiments described and/or suggestedherein may preferably be capable of identifying the storage location ofdata to be reclaimed and switching between the plurality of storagelocations such as source tape media 134 a-134 c, and disk cache 122a-122 x from which tape drives 132 s, 132 t are reading the data to bereclaimed.

Although at least two tape drives 132 s, 132 t are preferably occupiedduring the reclamation process, the two tape drives 132 s, 132 t may notalways be occupied at the same time. For example, if the data to bereclaimed is in a pre-migrated state, that pre-migrated data can be readdirectly from the disk cache 122 a-122 x to target media 134 t by tapedrive 132 t. Thus, the period of time during which the two tape drives132 s, 132 t are needed to be used at the same time can be shortened andthe overall reclamation period can be shortened. For example, the IBM®TS7700 starts reclamation when the proportion of valid data to all datawritten to the tape becomes equal to or lower than 35 percent; i.e. only35% of the data written on the tape drive is valid. If an IBM® 3592 JDmedium having the capacity of 10 terabytes should be reclaimed and allpieces of data are read from the tape, it is necessary to read data ofup to 3.5 terabytes (=10 TB*35%). Here, if the data has beensuccessfully read at the maximum data transfer rate (360 MB/sec) of theIBM® TS1150 tape drive, then the conventional scheme will use the driveof the source of reclamation for about 2 hours 49 minutes 54 seconds(=3.5 (TB)/360 (MB/sec)). In contrast, if the source from which the datais reach is switched between the when the proposed scheme is used, theperiod of time during which the drives are needed to be used can beshortened in accordance with the proportion of the data in thepre-migrated state to all the data in the source tape to be reclaimed.For example, when 50 percent of 3.5 terabytes of data is also stored inthe primary storage unit, it is made possible to shorten the period oftime during which the drive of the source of reclamation is used to a 50percent (=about 1 hour 25 minutes).

In one or more embodiments described herein, a novel reclamationfunction for reclaiming data from the source media 134 to the targetmedia 134 t, in which the tape drives 132 s, 132 t switch between theplurality of tape media 134 a-134 c and disk cache 122 a-122 x fromwhich the data to be reclaimed is being read, may be described as beingincorporated into the hierarchical storage system 100.

For this purpose, as shown in FIG. 4, the reclamation module 230includes a data locator module 232, a storage media selector 234, a copymodule 236 and a migration module 238. In an exemplary embodiment, acache 240 (or buffer) for temporarily storing data transferred from thesource tape media 134 a-134 c is also utilized. The disk cache 122 maybe a source storage device that stores a plurality of files as a targetfor migration which is performed during the spare time of thereclamation process.

The data locator module 232 may be configured to identify data stored onthe source media 134 a-134 c and/or disk cache 122 a-122 x to bereclaimed, i.e. read from the source media 134 a-134 c and/or disk cache122 a-122 x and then written to the target media 134 t. The data locatormodule 232 may further identify the state of the data to be read fromthe source media 134 a-134 c and/or disk cache 122 a-122 x. For example,the data locator module 232 may identify the data stored on the sourcemedia 134 a-134 c and/or disk cache 122 a-122 x as being in, forexample, a pre-migrated state, a resident state, or a migrated state.

The storage media selector 234 is configured to select between thesource tape media 134 a-134 c and/or disk cache 122 a-122 x from whichthe identified source data for reclamation is to be read and written totape drive 132 t. The storage media selector 234 may switch betweensource tape media 134 a-134 c and/or disk cache 122 a-122 x based on thestorage location of the identified source data. For example, identifiedsource data may be in a pre-migrated state and thus the identifiedsource data for reclamation is stored in both a tape media 134 and adisk cache 122. In one embodiment of the invention, all identifiedsource data for reclamation in a pre-migration state will be read fromthe disk cache 122 a-x written to target tape media 134 t by tape drive134 t and all identified source data for reclamation in a migrated statewill be read from the source tape media 134 a-134 c by tape drive 132 sand written to target media 134 t by tape drive 132 t.

The copy module 236 is configured to read the identified source data forreclamation from the source media 134 a-134 c by the source tape drive132 s and to write the identified source data to the target media 134 tby the target tape drive 132 t. The copy module 236 may write theidentified source data for reclamation to the target media 134 t afterthe migration of the identified source data for reclamation iscompleted. In a particular embodiment, files may be copied from thesource media 134 a-134 c as the copy source to the target media 134 t asthe copy destination in a one by one manner by using the copy (CP) orsecure copy (SCP) command.

Instead of reading from the source media 134 to the disk cache 122 tochange the file state to “pre-migrated” state, the files are directlyread from the source media 134 a-134 c. Thus, copy from the source media134 a-134 c to the target media 134 t is conducted while leaving thefile state to be “migrated” state.

The copy module 236 may read data from the source media 134 into thecache 240 dedicated for data transfer in the reclamation, and write theread data to the target media 134 t. Note that the tape drive 132 maynot serve as an initiator as in the case of the extended copy for directtransfer between the drives. Two tape drives 132 s and 132 t are usedtogether, and data copy is carried out between the source media 134 andthe target media 134 t in a one-to-one manner.

The migration module 238 is configured to migrate the migrationidentified source data for reclamation from the shared disk array 120 tothe target media 134 t by the target tape drive 132 t while reading(e.g., which may include locating and/or reading) the identified sourcedata for reclamation from the source media 134 a-124 c by the sourcetape drive 132 s. In contrast to the reclamation where reading from thesource media 134 strongly affects performance, writing the migrationidentified source data for reclamation to the target media 134 tcontrols speed of writing the target media 134 t predominantly since thereading speed from the disk cache 122 is much faster than the writingspeed to the target media 134 t.

Referring to FIG. 5, a method 300 for reclaiming data from a sourcemedium to a target medium in a storage system according to an embodimentof the present invention is described.

Referring to block 310, the node 112 generates a list of data located onsource tape media 134 a-134 c in tape library 130 to be reclaimed. Thedata to be reclaimed from source tape media 134 a-134 c may hereinafterbe referred to as reclamation target data. The list of reclamationtarget data may be generated in response to receiving a request forreclamation from one or more users. In another embodiment of theinvention, the list of reclamation target data may be generated bydetermining that a condition that triggers reclamation is met. Forexample, when the proportion of valid data on tape media 134 a-134 c toall data on tape media 134 a-134 c is lower than 35 percent, i.e. 35percent or less of the data on tape media 134 a-c is valid, thereclamation process may be automatically triggered by the node 112.

Referring to block 312, a target tape media 134 t to which thereclamation target data is to be written is selected by node 112.

Referring to block 314, node 112 analyzes the generated list ofreclamation target data and identifies all reclamation target data thatis in a pre-migrated state.

Referring to block 316, the node 112 locates the pre-migratedreclamation target data on the disk cache 122 a-122 x in shared diskarray 120 and reads the pre-migrated reclamation target data on the diskcache 122 a-122 x using the migration module 238.

Referring to block 318, the node 112 writes the pre-migrated reclamationtarget data of the disk cache 122 a-122 x to the target tape media 134t.

Referring to block 320, the node 112 determines whether the reclamationof the pre-migrated data is finished or if further pre-migratedreclamation target data on the generated list needs to be read andwritten to the target tape media 134 t. If the node 112 determines thatthe reclamation is not finished and further pre-migrated reclamationtarget data remains to be reclaimed at block 320 (NO), then the processloops back to block 316. If the node 112 determines that allpre-migrated reclamation target data has been read and written to thetarget tape media 134 t, the process may proceed to block 322.

Referring to block 322, node 112 analyzes the generated list ofreclamation target data and identifies all reclamation target data thatis in a migrated state.

Referring to block 324, the node 112 locates the migrated reclamationtarget data on the source tape media 134 a-134 c in the tape library 130and the source tape drive 132 s reads the migrated reclamation targetdata on the source tape media 134 a-134 c using the copy module 236.

Referring to block 326, the node 112 writes the migrated reclamationtarget data of the source tape media 134 a-134 c to the target tapemedia 134 t.

Referring to block 328, the node 112 determines whether the reclamationof the migrated data is finished or if further migrated reclamationtarget data on the generated list needs to be read and written to thetarget tape media 134 t. If the node 112 determines that the reclamationis not finished and further migrated reclamation target data remains tobe reclaimed at block 328 (NO), then the process loops back to block324. If the node 112 determines that all migrated reclamation targetdata has been read and written to the target tape media 134 t, theprocess may proceed to end.

Referring to FIG. 6, a system 1000 includes a computer system orcomputer 1010 shown in the form of a generic computing device. Themethod 300, for example, may be embodied in a program(s) 1060 (FIG. 6)embodied on a computer readable storage device, for example, generallyreferred to as memory 1030 and more specifically, computer readablestorage medium 1050 as shown in FIG. 6. For example, memory 1030 caninclude storage media 1034 such as RAM (Random Access Memory) or ROM(Read Only Memory), and cache memory 1038. The program 1060 isexecutable by the processing unit or processor 1020 of the computersystem 1010 (to execute program steps, code, or program code).Additional data storage may also be embodied as a database 1110 whichcan include data 1114. The computer system 1010 and the program 1060shown in FIG. 6 are generic representations of a computer and programthat may be local to a user, or provided as a remote service (forexample, as a cloud based service), and may be provided in furtherexamples, using a website accessible using the communications network1200 (e.g., interacting with a network, the Internet, or cloudservices). It is understood that the computer system 1010 alsogenerically represents herein a computer device or a computer includedin a device, such as a laptop or desktop computer, etc., or one or moreservers, alone or as part of a datacenter. The computer system caninclude a network adapter/interface 1026, and an input/output (I/O)interface(s) 1022. The I/O interface 1022 allows for input and output ofdata with an external device 1074 that may be connected to the computersystem. The network adapter/interface 1026 may provide communicationsbetween the computer system a network generically shown as thecommunications network 1200.

The computer 1010 may be described in the general context of computersystem-executable instructions, such as program modules, being executedby a computer system. Generally, program modules may include routines,programs, objects, components, logic, data structures, and so on thatperform particular tasks or implement particular abstract data types.The method steps and system components and techniques may be embodied inmodules of the program 1060 for performing the tasks of each of thesteps of the method and system. The modules are generically representedin FIG. 6 as program modules 1064. The program 1060 and program modules1064 can execute specific steps, routines, sub-routines, instructions orcode, of the program.

The method of the present disclosure can be run locally on a device suchas a mobile device, or can be run a service, for instance, on the server1100 which may be remote and can be accessed using the communicationsnetwork 1200. The program or executable instructions may also be offeredas a service by a provider. The computer 1010 may be practiced in adistributed cloud computing environment where tasks are performed byremote processing devices that are linked through a communicationsnetwork 1200. In a distributed cloud computing environment, programmodules may be located in both local and remote computer system storagemedia including memory storage devices.

More specifically, as shown in FIG. 6, the system 1000 includes thecomputer system 1010 shown in the form of a general-purpose computingdevice with illustrative periphery devices. The components of thecomputer system 1010 may include, but are not limited to, one or moreprocessors or processing units 1020, a system memory 1030, and a bus1014 that couples various system components including system memory 1030to processor 1020.

The bus 1014 represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnects (PCI) bus.

The computer 1010 can include a variety of computer readable media. Suchmedia may be any available media that is accessible by the computer 1010(e.g., computer system, or server), and can include both volatile andnon-volatile media, as well as, removable and non-removable media.Computer memory 1030 can include additional computer readable media 1034in the form of volatile memory, such as random access memory (RAM),and/or cache memory 1038. The computer 1010 may further include otherremovable/non-removable, volatile/non-volatile computer storage media,in one example, portable computer readable storage media 1072. In oneembodiment, the computer readable storage medium 1050 can be providedfor reading from and writing to a non-removable, non-volatile magneticmedia. The computer readable storage medium 1050 can be embodied, forexample, as a hard drive. Additional memory and data storage can beprovided, for example, as the storage system 1110 (e.g., a database) forstoring data 1114 and communicating with the processing unit 1020. Thedatabase can be stored on or be part of a server 1100. Although notshown, a magnetic disk drive for reading from and writing to aremovable, non-volatile magnetic disk (e.g., a “floppy disk”), and anoptical disk drive for reading from or writing to a removable,non-volatile optical disk such as a CD-ROM, DVD-ROM or other opticalmedia can be provided. In such instances, each can be connected to bus1014 by one or more data media interfaces. As will be further depictedand described below, memory 1030 may include at least one programproduct which can include one or more program modules that areconfigured to carry out the functions of embodiments of the presentinvention.

The method 300 (FIG. 5), for example, may be embodied in one or morecomputer programs, generically referred to as a program(s) 1060 and canbe stored in memory 1030 in the computer readable storage medium 1050.The program 1060 can include program modules 1064. The program modules1064 can generally carry out functions and/or methodologies ofembodiments of the invention as described herein. The one or moreprograms 1060 are stored in memory 1030 and are executable by theprocessing unit 1020. By way of example, the memory 1030 may store anoperating system 1052, one or more application programs 1054, otherprogram modules, and program data on the computer readable storagemedium 1050. It is understood that the program 1060, and the operatingsystem 1052 and the application program(s) 1054 stored on the computerreadable storage medium 1050 are similarly executable by the processingunit 1020.

The computer 1010 may also communicate with one or more external devices1074 such as a keyboard, a pointing device, a display 1080, etc.; one ormore devices that enable a user to interact with the computer 1010;and/or any devices (e.g., network card, modem, etc.) that enables thecomputer 1010 to communicate with one or more other computing devices.Such communication can occur via the Input/Output (I/O) interfaces 1022.Still yet, the computer 1010 can communicate with one or more networks1200 such as a local area network (LAN), a general wide area network(WAN), and/or a public network (e.g., the Internet) via networkadapter/interface 1026. As depicted, network adapter 1026 communicateswith the other components of the computer 1010 via bus 1014. It shouldbe understood that although not shown, other hardware and/or softwarecomponents could be used in conjunction with the computer 1010.Examples, include, but are not limited to: microcode, device drivers1024, redundant processing units, external disk drive arrays, RAIDsystems, tape drives, and data archival storage systems, etc.

It is understood that a computer or a program running on the computer1010 may communicate with a server, embodied as the server 1100, via oneor more communications networks, embodied as the communications network1200. The communications network 1200 may include transmission media andnetwork links which include, for example, wireless, wired, or opticalfiber, and routers, firewalls, switches, and gateway computers. Thecommunications network may include connections, such as wire, wirelesscommunication links, or fiber optic cables. A communications network mayrepresent a worldwide collection of networks and gateways, such as theInternet, that use various protocols to communicate with one another,such as Lightweight Directory Access Protocol (LDAP), Transport ControlProtocol/Internet Protocol (TCP/IP), Hypertext Transport Protocol(HTTP), Wireless Application Protocol (WAP), etc. A network may alsoinclude a number of different types of networks, such as, for example,an intranet, a local area network (LAN), or a wide area network (WAN).

In one example, a computer can use a network which may access a websiteon the Web (World Wide Web) using the Internet. In one embodiment, acomputer 1010, including a mobile device, can use a communicationssystem or network 1200 which can include the Internet, or a publicswitched telephone network (PSTN) for example, a cellular network. ThePSTN may include telephone lines, fiber optic cables, microwavetransmission links, cellular networks, and communications satellites.The Internet may facilitate numerous searching and texting techniques,for example, using a cell phone or laptop computer to send queries tosearch engines via text messages (SMS), Multimedia Messaging Service(MMS) (related to SMS), email, or a web browser. The search engine canretrieve search results, that is, links to websites, documents, or otherdownloadable data that correspond to the query, and similarly, providethe search results to the user via the device as, for example, a webpage of search results.

It is to be understood that although this disclosure includes a detaileddescription on cloud computing, implementation of the teachings recitedherein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g., networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported, providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third-party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third-partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure that includes anetwork of interconnected nodes.

Referring now to FIG. 7, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 includes one or morecloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 9 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 8, a set of functional abstraction layers providedby cloud computing environment 50 (FIG. 7) is shown. It should beunderstood in advance that the components, layers, and functions shownin FIG. 9 are intended to be illustrative only and embodiments of theinvention are not limited thereto. As depicted, the following layers andcorresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include: mainframes 61; RISC(Reduced Instruction Set Computer) architecture based servers 62;servers 63; blade servers 64; storage devices 65; and networks andnetworking components 66. In some embodiments, software componentsinclude network application server software 67 and database software 68.

Virtualization layer 70 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers71; virtual storage 72; virtual networks 73, including virtual privatenetworks; virtual applications and operating systems 74; and virtualclients 75.

In one example, management layer 80 may provide the functions describedbelow. Resource provisioning 81 provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 82provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may include applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 83 provides access to the cloud computing environment forconsumers and system administrators. Service level management 84provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 85 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 90 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 91; software development and lifecycle management 92; virtualclassroom education delivery 93; data analytics processing 94;transaction processing 95; and data reclamation 96.

The programs described herein are identified based upon the applicationfor which they are implemented in a specific embodiment of theinvention. However, it should be appreciated that any particular programnomenclature herein is used merely for convenience, and thus theinvention should not be limited to use solely in any specificapplication identified and/or implied by such nomenclature.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the blocks may occur out of theorder noted in the Figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

While steps of the disclosed method and components of the disclosedsystems and environments have been sequentially or serially identifiedusing numbers and letters, such numbering or lettering is not anindication that such steps must be performed in the order recited, andis merely provided to facilitate clear referencing of the method'ssteps. Furthermore, steps of the method may be performed in parallel toperform their described functionality.

What is claimed is:
 1. A method for copying data from source media totarget media in a storage system, the method comprising: generating alist of data to be copied from a plurality of source media to a targetmedium, by a node in a computer system; identifying, by the node, afirst type of data in the generated list of data, the first type of databeing pre-migrated data; reclaiming, by the node using a first drive,the first type of data from a primary storage tier to the target medium,the target medium associated with the first drive; identifying, by thenode, a second type of data in the generated list of data, the secondtype of date being migrated data; and reclaiming, by the node using thefirst drive and a second drive, the second type of data from at leastone secondary source medium on a secondary storage tier to the targetmedium, the at least one secondary source medium associated with thesecond drive.
 2. A method as in claim 1, wherein the first type of datais stored on both the primary storage tier and the secondary storagetier.
 3. A method as in claim 1, wherein the second type of data isstored only on the secondary storage tier.
 4. A method as in claim 1,wherein reclaiming the pre-migrated data from a primary storage tier toa target medium comprises: reading, by the node, the pre-migrated dataon the primary storage tier; and writing, by the first drive, the readpre-migrated data to the target medium.
 5. A method as in claim 1,wherein reclaiming the migrated data from a source medium to a targetmedium comprises: reading, by the second drive, the migrated data fromthe at least one source medium; and writing, by the first drive, themigrated data to the target medium.
 6. A method as in claim 1, whereinreclaiming the pre-migrated data from a primary storage tier to a targetmedium is 50 percent faster than reclaiming the migrated data from atleast one source medium to a target medium.
 7. A method as in claim 1,wherein the source medium and the target medium are tape media, whereinthe first drive and the second drive are tape drives, wherein theprimary storage tier is a disk tier in a hierarchical storage system,and wherein the tape drives constitute a tape media tier in thehierarchical storage system.
 8. A computer program product for copyingdata from source media to target media in a storage system, the computerprogram product comprising: a computer-readable storage medium havingprogram instructions embodied therewith, wherein the computer readablestorage medium is not a transitory signal per se, the programinstructions executable by a computer to cause the computer to perform amethod, comprising: generating a list of data to be copied from aplurality of source media to a target medium, by a node in a computersystem; identifying, by the node, a first type of data in the generatedlist of data, the first type of data being pre-migrated data;reclaiming, by the node using a first drive, the first type of data froma primary storage tier to the target medium, the target mediumassociated with the first drive; identifying, by the node, a second typeof data in the generated list of data, the second type of date beingmigrated data; and reclaiming, by the node using the first drive and asecond drive, the second type of data from at least one secondary sourcemedium on a secondary storage tier to the target medium, the at leastone secondary source medium associated with the second drive.
 9. Thecomputer program product as in claim 8, wherein the first type of datais stored on both the primary storage tier and the secondary storagetier.
 10. The computer program product as in claim 8, wherein the secondtype of data is stored only on the secondary storage tier.
 11. Thecomputer program product as in claim 8, wherein reclaiming thepre-migrated data from a primary storage tier to a target mediumcomprises: reading, by the node, the pre-migrated data on the primarystorage tier; and writing, by the first drive, the read pre-migrateddata to the target medium.
 12. The computer program product as in claim8, wherein reclaiming the migrated data from a source medium to a targetmedium comprises: reading, by the second drive, the migrated data fromthe at least one source medium; and writing, by the first drive, themigrated data to the target medium.
 13. The computer program product asin claim 8, wherein reclaiming the pre-migrated data from a primarystorage tier to a target medium is 50 percent faster than reclaiming themigrated data from at least one source medium to a target medium. 14.The computer program product as in claim 8, wherein the source mediumand the target medium are tape media, wherein the first drive and thesecond drive are tape drives, wherein the primary storage tier is a disktier in a hierarchical storage system, and wherein the tape drivesconstitute a tape media tier in the hierarchical storage system.
 15. Asystem for copying data from source media to target media in a storagesystem, the system comprising: a computer system comprising, aprocessor, a computer readable storage medium, and program instructionsstored on the computer readable storage medium being executable by theprocessor to cause the computer system to: generate a list of data to becopied from a plurality of source media to a target medium, by a node ina computer system; identify, by the node, a first type of data in thegenerated list of data, the first type of data being pre-migrated data;reclaim, by the node using a first drive, the first type of data from aprimary storage tier to the target medium, the target medium associatedwith the first drive; identify, by the node, a second type of data inthe generated list of data, the second type of date being migrated data;and reclaim, by the node using the first drive and a second drive, thesecond type of data from at least one secondary source medium on asecondary storage tier to the target medium, the at least one secondarysource medium associated with the second drive.
 16. A computer system asin claim 15, wherein the first type of data is stored on both theprimary storage tier and the secondary storage tier.
 17. A computersystem as in claim 15, wherein the second type of data is stored only onthe secondary storage tier.
 18. A computer system as in claim 15,wherein the program instruction to reclaim the pre-migrated data from aprimary storage tier to a target medium comprises program instructionto: read, by the node, the pre-migrated data on the primary storagetier; and write, by the first drive, the read pre-migrated data to thetarget medium.
 19. A computer system as in claim 15, wherein the programinstruction to reclaim the migrated data from a source medium to atarget medium comprises program instruction to: read, by the seconddrive, the migrated data from the at least one source medium; and write,by the first drive, the migrated data to the target medium.
 20. Acomputer system as in claim 15, wherein reclaiming the pre-migrated datafrom a primary storage tier to a target medium is 50 percent faster thanreclaiming the migrated data from at least one source medium to a targetmedium.